Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1999-06-18
2002-06-04
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S107000, C528S113000, C528S114000, C528S118000, C528S121000, C528S122000, C528S229000, C528S246000, C525S176000, C427S384000, C427S385500, C427S386000
Reexamination Certificate
active
06399742
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to curable compositions and more particularly to low VOC (volatile organic component) ambient temperature curable coating compositions containing low viscosity imine reactive diluents, which are especially suited for use in automotive refinish applications.
Due to increasingly stringent environmental regulations and the demand for better performance, reactive diluents/oligomers are becoming crucial components in a variety of automotive coating formulations. This is especially true for high solids coatings. Such products are typically enamels because low molecular weight building blocks can be used to form cross-linked networks that provide robust films. The rate of cure is therefore important since the rate of film formation determines autobody shop throughput and profitability. Certain imines and imine-containing coating compositions are known. Representative disclosures can be found in U.S. Pat. No. 5,198,524, U.S. Pat. No. 3,668,183, U.S. Pat. No. 4,772,680 and U.S. Pat. No. 5,288,802. None of these publications discloses the imines of this invention nor coatings that contain them characterized by low volatile organic content (VOC), good sprayability, quick cure and hard, solvent-resistant films formed therefrom.
SUMMARY OF THE INVENTION
The present invention is directed to an imine reactive diluent of Formula I:
wherein
R and R
1
are the same or different, and are independently selected from the group consisting of hydrogen, a C
6
to C
50
, preferably C
6
to C
6
to C
14
, more preferably C
6
to C
8
aromatic structure, C
1
to C
50
alkyl moiety having a linear aliphatic, branched aliphatic, or cycloaliphatic structure. When the alkyl moiety has the cycloaliphatic structure it preferably includes 6 to 14 carbon atoms, when it has the linear or branched structure it preferably includes 1 to 10 carbon atoms.
R
2
and R
3
are the same or different, and are selected from the group consisting of a C
1
to C
50
, preferably C
1
to C
10
, more preferably C
1
to C
5
linear aliphatic, branched aliphatic, and cycloaliphatic structure. When R
2
and R
3
have the cycloaliphatic structure they preferably include 6 to 14 carbon atoms, when they have the linear structure they preferably include 2 to 10 carbon atoms and when they have the branched structure they preferably include 3 to 10 carbon atoms.
Y is a residue with a weight average molecular weight up to about 100,000, preferably 14 to 100,000, more preferably 14 to 50,000, most preferably 28 to 20,000 and having said linear aliphatic, branched aliphatic, cycloaliphatic, aromatic structure, or a combination thereof;
wherein R
1
,R
2
,R
3
and Y are free from a hydrogen bonding group; and
x is an integer of at least 2, preferably 2 to 50, more preferably 2 to 10 and most preferably 2 to 4. Preferred imine reactive diluents of Formula I are those in which R and R
1
are not both isopropyl.
R
2
, R
3
or Y of the imine reactive diluent of Formula I may include one or more heteroatoms, preferably 1 to 3 heteroatoms in R
2
and R
3
, and preferably 1 to 30 in Y. Preferred heteroatoms include O, S, Si and P but not N. To achieve good coating solution viscosity, there will be no hydrogen atoms on any of the heteroatoms.
The imine reactive diluent 1 is a ketimine when R and R
1
are not hydrogen and an aldimine when R
1
is not hydrogen.
Some of the preferred imine reactive diluent of Formula I include the following:
Even more preferred imine reactive diluents of Formula I is:
I. A tetraketimine having the formula:
II. A hexaketimine having the formula:
III. An octaketimine having the formula:
The imine reactive diluent of the Formula I is produced by reacting, in the presence of a Lewis acid catalyst and a reactive solvent, an acrylate group containing organic compound having the formula:
with 1.0 mole of an imine reactant per mole of acrylate groups in the compound.
The organic compound may be obtained by conventional means, such as by reacting a polyol having the desired number of functionalities with an acryloyl chloride or acrylic acid. Typically, a free radical scavenger, such as monomethyl ether hydroquinone, generally at 50 to 100 ppm of the reaction mixture, is added to prevent undesired polymerization of the resulting acrylate groups.
The imine reactant may be obtained by first dissolving a corresponding amine compound which includes R
2
and R
3
functionalities into an excess amount of a reactive solvent, generally a ketone for producing a ketimine reactive diluent and an aldehyde for producing an aldimine reactive diluent. The reactive solvent contains the desired R and R
1
functionalities. Some of the preferred ketones include acetone, methyl ethyl ketone, methyl pentyl ketone and preferably methyl isobutyl ketone. Some of the preferred aldehydes include propionaldehyde, butyraldehyde and isobutyraldehyde. The dissolved amine compound reacts with the reactive solvent at elevated temperatures to produce the imine reactant of the following formula:
The imine reactant is then reacted with an organic compound having at least two acrylate groups to produce the imine reactive diluent. Depending upon the functionalities present on the imine reactant and the organic compound, the reaction is generally carried out at about −10° C. to 100° C., preferably, at about 0° C. to 60° C. and more preferably at about 15° C. to 35° C. in the presence of an excess amount of the reactive solvent. Typical Lewis catalyst suitably for use in the present invention is selected from at least one member of the group consisting of FeCl
3
, acidic gamma alumina, Yb(CF
3
SO
3
)
3
, Sc(CF
3
SO
3
)
3
, tetraisopropyl titanate, and La(CF
3
SO
3
)
3
. The amount of catalyst employable in the method of the present invention generally varies in the range of 0.01 to 20, preferably in the range of from 0.1 to 8 and more preferably in the range of from 3 to 7, all in weight percentages based on the weight of residue Y in the Formula I above. The applicants unexpectedly discovered a major improvement of the method of the present invention in that it permits one to produce the imine reactive diluent in the same reactor, without transferring the reaction mixture to any other reactors. The single reactor preparation makes the process simple-to-operate, safe and efficient.
The excess amount of the reactive solvent present in the reaction mixture is adjusted to provide a coating composition containing the imine reactive diluent of the present invention with a desired amount of VOC.
Specifically, an imine reactant may be obtained by dissolving diethylene triamine in an excess amount of 4-methyl-2-pentanone reactive solvent and then elevating the reaction mixture under reflux to about 142° C. for producing the imine reactant of the following formula:
Alternatively, the foregoing triamine-bisketimine may be obtained from Air Products of Allentown, Pa. Triamine-bisketimine (imine reactant) is then reacted in the same reactor, in the presence of a Lewis catalyst with an organic compound of the following formula:
to produce the imine reactive diluent.
The present invention is also directed to a two-pack coating composition comprising a component (i) and a component (ii) wherein:
(i) comprises from 10 to 90, preferably 20 to 80 and more preferably 30 to 70 weight percent of an oligomer or a polymer having a weight average molecular weight not exceeding about 5,000, preferably 100 to 5,000, more preferably 200 to 4,500 and most preferably 300 to 4,000, and functionality selected from one or more of acetoacetate, acrylate, isocyanate, epoxide and cyclic carbonate moieties; and
(ii) comprises from 10 to 90, preferably 20 to 80 and more preferably 30 to 70 weight percent of an imine reactive diluent having a weight average molecular weight from about 100 to 100,000, preferably 200 to 100,000, more preferably 250 to 50,000 and most preferably 300 to 20,000, and that is substantially free of hydrogen-bonding moieties and contains at least three imine groups per molecule wherein all percentages are bas
Deshmukh Sudhir G.
E. I. du Pont de Nemours and Company
Hampton-Hightower P.
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